Refrigerating system



Nov. 16, 1936. A. F. HOESEL REFRIGERATING SYSTEM Filed Nov. 25. 1935INVENTOQ Patented Nov. 10, 1936 PATENT OFFICE nrzrarenas'rmo SYSTEMAnthony F. Hoesel, Chicago. 111., assignor to Peerless Ice MachineCompany, Chicago, Ill.

Application November 23, 1935, Serial No. 51,222

11 Claims. (Cl. 62-6) I I'ioroed convection circulation type coolers,tion, of a temperature diflerential control used prior to my invention,operating on alternate ontime and oil-time cycles in respect to therefrigerant circulation through the cooler, had. their fans operatingeither continuously at a given speed or else the fan was stoppedwhenever the cooled compartment reached its desired minimum temperature.The fan, whenever the compartment reached the desired maximumtemperature, was again started. Whenever the fan was cyclicallyoperated, it was controlled either by a room thermostat or else inconjunction with the cyclical operation of. .the compressor circulatingthe refrigerant fluid. Both of these methods, of cyclically operatingthe fan, are so well known in the art that it is presumed unnecessary toelab- With an intermittently operated fan, the temperatures, throughoutthe cooled compartment, vary to a considerable extent during theoff-time period of the fan; alsoall of the disadvantages of thecontinuously operated fan, as outlined in the preceding paragraph, alsopersist.

One 01'. the objects of my invention is to provide a forced circulationof air, through a cooling unit, of such volume as will maintain adefinite temperature differential between the comparatively warm air,prior to its circulation through the cooling unit, and the cooled airissuing from the cooling unit. -In this manner, I am enabled to controlthe moisture content of the circulated I air.

Another object is to provide 'a decreased circulation of air, during thecompressor oil-time cycle, thereby allowing the circulated air to morereadily pick up moisturefrom the cooling unit surfaces, upon which themoisture is condensed and frozen during the compressor on-time cycle.

the elements of the invention.

Figure 2 is an elevational view, partly in seccased. The conduits 4 and5 serve as conductors of the refrigerant, to and from the cooling unit3, andeare connected to a refrigerant compressorcondenser system notshown.

An electric motor 6 operates the fan I, forcing the air through theencased cooling unit 3 and in the direction indicated by the arrows.

A temperature diflerential control 8, of which the temperatureresponsive bulb 9 is subject to the temperature of the refrigeratedspace, and of which the temperature responsive bulb I 0 is subject tothe temperature of the air forced through the cooling'unit 3, controlsthe resistance of the electrical circuit II and I2, connectcd to asuitable source of electrical energy,

and which energize the electric motor 6, rotating thefan I.

In Figure 2, the temperature differential control 8 comprises a base l3,upon which is mounted a flexible bellows member H, which, with'itsassociated temperature responsive bulb 9, forms a closed system chargedwith a temperature pressure responsive fluid.

A lever 16, pivoted at point I! and oscillating thereabout, subject tothe movements of the flexible bellows members l4 and I5; presses againstthereby ,an insulator disc l8 between which and the insulator disc 19, amultiplicity of carbon discs 20 are placed. A spring 2| is recessed intothe flange 2 2 of the leg 23 of the base 13. I

The extreme end discs, of the carbon pile 20, are connected to the leadsII and 24 of an electrical circuit.

An insulating bushing 25, mounted upon the flange 22, and slotted at itsupper end and at its lower end for the passage of the electrical circuitconduits 24 and ill to their respective carbon end discs of the carbondisc pile 20, serves to keep the carbon discs 20, insulators l8 and ISin alignment.

The lever l6, at its free end, has a boss 26 having a bore 21 engagingan end of the tension spring 28-, the other end of which engages a bore29 of the adjusting screw 30,-positioned within a suitable opening inthe base I3. The adjusting nut 3| serves to lengthen or shorten thetension spring 28, thereby increasing or decreasing the pressure of thelever- I 6 upon the carbon disc pile assembly, thereby decreasing orincreasing,

respectively, the electrical resistance of the carbon pile assembly.

The downward movement, of the lever I6, is limited by the abutment stop32 integral with the base l3.

Having described the details of the invention,

I shall now describe its operation. Assuming the space I at an elevatedtemperature and the starting of the refrigerant circulation through therefrigerant conduits l and 5 and the cooling unit 3, thereby reducingthe temperature of the cooling unit 3 in the casing 2, the cooled airpassing by the temperature responsive bulb HI reduces the pressurewithin the flexible bellows member l5, thereby tending to allow theflexible bellows member I, which contains a greater pressure, due to thehigher temperature of the temperature responsive bulb 9, to exert agreater force against the lever l6, which, increasing the pressureexerted upon the carbon discs 20, decreases the resistance to theelectrical current flow through the carbon discs 20 and, in consequence,the motor 6, becoming more highly energized through the increasedelectrical current flow in the circuit conduits II and I2, the fan I isoperated at an increased speed.

with a given temperature of the cooling unit 3 in the casing 2, and acertain increased temperature of the air prior to its passage throughthe cooling unit, it follows that a decrease in the rate of the aircirculated through the cooling unit must result in the lower volume ofair being at a lower temperature at the exit from the cooling unit.Conversely, an increase in the rate of the air circulated through thecooling unit must result in the increased volume of air, passing throughthe cooling unit, being at a higher temperature at the exit from thecooling unit.

As the temperature of the cooled space drops, the pressure in thebellows member l4 decreases. This tends to decrease the pressure uponthe carbon disc 2|, increase the resistance of the electrical circuitand decrease the speed of the motor 6 and fan I; however, thetemperature of the air, passing through the cooling unit 3 and passingby the temperature responsive bulb III,

also drops, and this, reducing the temperature of the temperatureresponsive bulb I0, decreases the pressure in the bellows'member I5,which tends to allow the bellows member H to press with greater forceupon the lever l6 and, thereby increase the pressure upon the carbondiscs 20, decreasing their electrical resistance, and thereby increasingthe speed of the motor 6 and fan I. Since these opposing tendenciespractically balance each other, the net result is that the fan tends tooperate at a continuous speed during the flow of refrigerant through thecooling unit.

Assuming the system in operation as previously described and thecirculation of refrigerant, in the cooling unit, greatly increased. Thisresults in the air, passing by the temperature responsive bulb l0, beingreduced in temperature below that previously. The temperature responsivebulb l drops in temperature and the flexible bellows member l5 presses,with decreased force, against the lever I6 and the pressure of thecarbon discs 20 is increased, thereby decreasing their electricalresistance and speeding up the electric motor 6 and fan 1 to such speedas will force sufllcient air through the cooling unit 3, so that thecooled air passing by the temperature responsive bulb Ill again reachesapproximately its same temperature as existed before the increasedcirculation of the refrigerant.'

Assuming the system in operation,and the compressor-condens'er systemthen closed down. The circulation of refrigerant ceases. The coolingunit 3 increases intemperature and the air, passing by the temperatureresponsive bulb l0, raises the temperature of the temperature responsivebulb I0, thereby increasing the force with which the flexible bellows l8presses against the lever I6 and decreasing the pressure of the carbondiscs 20, increases their electrical resistance and slows down the motor6 and fan I to the point where the decreased volume of air passing bythe bulb I0 is again of approximately the same temperature as before thestoppage of the refrigerant circulation.

Since the differential temperature control 8 operates to maintain aconstant temperature differential between the temperature responsivebulbs 9 and ID, the bulb 9 being at the higher or refrigerated spacetemperature, and the bulb l0 being at the lower or cooled airtemperature, it is very desirable to vary the temperature differentialin order to get certain desired conditions of moisture content of theair, also to regulate the normal maximum volume of air circulated by thefan I. For this purpose, I have incorporated an adjustment by means ofthe tension spring 28, adjusting screw 30 and the adjusting nut II. Byproper manipulation, the force exerted by the tension spring 28 upon thelever I6, is so regulated that the temperature bulb 9 must be thedesired temperature differential, above the temperature of thetemperature responsive bulb In, so that the pressure of the bellowsmember l4 will sufficiently counter-balance the pressure of the bellowsmember |5 plus the force of the tension spring 28, and compress thecarbon discs 20 sufficiently to maintain the speed of the fan 1 at thedesired condition of operation.

It is obvious that, since the control is operated by temperaturedifference, and since there may occur times when there is no temperaturedifference of the bulbs 9 and I0, some means must be employed toenergize the system until such time as a controlling temperaturedifference occurs. For this purpose, I employ the compression spring 2|,which, at all times, maintains a certain minimum compression of thecarbon discs 20, depending upon the amount of the compression of thespring 2| by means of adjustment of the adjusting screw 33, which is inthreaded engagement, as indicated, with the bore in which the spring 2|plays, and thereby maintains a certain maximum resistance to theelectric current flow through the carbon discs 20, whereby the fan 1, atall times, is never rotated below a certain minimum speed.

From the above, it is evident that I am enabled to maintain a certaintemperature difference between the air prior to and subsequent to itspassage through a cooling unit. If the temperature difference tends todecrease, the amount of air circulated tends to decrease. If thetemperature diiIerence tends to increase, the amount of air circulatedtends to increase.

With this method of operating a forced convection cooling system, Imaintain a definite balance between the heat absorption capacity of acooling unit, the amount of air circulated, the temperature differencebetween the cooled air and the main body of air; also I maintain, duringthe circulation of the refrigerant, a definite relationship between thetemperature of the cooling unit and the circulated air cooled therebyand, furthermore; I maintain a certain minimum air circulation at alltimes. All of these features are highly desirable and result in thebetter preservation of perishable foods, etc., especially those of adehumidifiable nature.

Assuming that we have a compartment to be maintained within thetemperature limits of 34 F. and 38" F., then the compressor would startthe refrigerant circulation whenever the compartment reached 38 F.temperature and, after a sufficient circulation of the refrigerant, thecompartment temperature would reach 34 F., at which time the compressorwould stop the circulation of refrigerant.

Just prior to the stopping of the refrigerant circulation, thetemperature of the compartment would be 34 F. and the temperature of theair discharged from the cooling unit would be approximately 22 F. Thiswould be a temperature differential of 12 F.

Just prior to the starting of the refrigerant circulation, thetemperature of the compartment would be 38 F. and the temperature of theair discharged from the cooling unit would be approximately 37 F. Thiswould be a temperature differential of 1 F.

Assuming the temperature differential control to be so adjusted as tooperate the fan motor at its maximum speed with an 11 F. differentialand to operate the fan motor at its minimum speed with a 1 F.temperature differential, then the temperature differential controlwould tend to gradually increase and decrease the fan motor speed duringthe refrigerant circulation on-time cycle and off-time cycle,respectively.

Under certain circumstances, it might prove advisable that the fan motorspeed decrease very rapidly from the beginning of the refrigerantcirculation off-time cycle and, in that case, I would adjust thetemperature differential control to operate the fan motor between itsminimum and maximum speeds with a very low temperature differentialvariation.

Assuming the same conditions of temperature differentials between thecooling unit discharge air and the compartment air, as explained above,if I adjust the temperature differential control to operate the fanmotor between its maximum and minimum speed with a temperaturedifferential variation of 2 F., then whenever the refrigerantcirculation ceases the temperature differential would quickly decrease 1F. since the air entering the cooling unit, at the start of therefrigerant circulation off-time cycle is 12 F. higher in temperaturethan the temperature of the air discharged from the cooling unit at thattime, and, therefore, the cooling unit would warm up sufficiently toslow the fan motor to its minimum speed in a very short period of time.

While the above is a specific concept of the invention, it is understoodthat I may employ variations from the same without departing from thespirit and scope of the invention, which is limited only by the claimshereto appended.

I claim:

1. In a refrigerating system the combination of a cooling unit, means tocirculate air through the cooling unit and means responsive to thetemperature differential between the circulated air entering and the airleaving the cooling unit to control the air circulating means.

'2. In a refrigerating system the combination of a cooling unit, meansto circulate air through the cooling unit and means responsive to thetemperature differential between the circulated air entering and the airleaving the cooling unit to control the air circulating means so as to1ncrease the volume of the circulated air upon an increase of thetemperature differential.

3. In a refrigerating system the combination of a cooling unit, means tocirculate air through the cooling unit and means responsive to thetemperature differential between the circulated air entering and the airleaving the cooling unit to control the air circulating means so as todecrease the volume of the circulated air upon a decrease of thetemperature differential.

4. In a refrigerating system the combination of a cooling unit, means tocirculate air through the cooling unit and means responsive to thetemperature differential between the circulated air entering and the airleaving the cooling unit to control the air circulating means so as toincrease or decrease the volume of the circulated air upon an increaseor decrease, respectively, of the temperature differential.

5. In a refrigerating system the combination of a cooling unit, means tocontinuously circulate air through the cooling unit and means responsiveto the temperature differential between the circulated air entering andthe air leaving the cooling unit to control the air circulating means,the said temperature differential responsive means being so limited, inits control of the said air circulating means, as to maintain at least acertain minimum volume of air circulation under any condition oftemperatures.

6. In a refrigerating system the combination of a cooling unit, means tocontinuously circulate air through the cooling unit and meanscontrolling the air circulating means to a predetermined minimum volumeof circulation whenever the cooling unit temperature increases abovethat of its normal operating temperature.

7. In a refrigerating system, the combination of a fan to circulate airthrough a cooling unit, control means, responsive to the temperaturedifferential between the temperature of the air leaving the cooling unitand the temperature of the air prior to its circulation through thecooling unit, to increase the speed of the fan upon an increase ofthetemperature differential.

8. In a refrigerating system, the combination of a fan to circulate airthrough a cooling unit, control means, responsive to the temperaturedifferential between the temperature of the air leaving the cooling unitand the temperature of the air prior to its circulation through thecooling unit, to decrease the speed of the fan upon a decrease of thetemperature differential.

9. In a refrigerating system. the combination of a fan to circulate air,past surfaces cooled by a circulating refrigerant at some predeterminedmaximum volume during the circulation of refrigerant and means todecrease the air circulation to some predetermined minimum volume duringthe stoppage of the refrigerant circulation.

10. In a forced air circulation refrigerating system, an'automaticcontrol, responsive to temperature variations, and which tends toincrease the air circulation upon a decrease in temperature of thecirculated air.

11. In a forced air circulation refrigerating system, an automaticcontrol, responsive to temperature variations, and which tends todecrease the air circulation upon an increase in temperature of thecirculated air.

ANTHONY F. HOESEL.

